Prema Pradipa by Srila Bhaktivinoda Thakur

 I found it here:

https://bhaktivinodainstitute.org/writings/books/prema-pradipa/

Important points:

Hence, yoga system is not wrong, its just too difficult to follow. It is easy that we perform the astang yoga, attain siddhis, and since till that state, we have not developed the love of the Godhead, we may begin to use these siddhis for our sense gratification. In this way, we will fall down again to a level where we are farther away from Krishna than when we had started the yoga practices. 

But, if we think of bhakti, the goal and the means are the same. Hence, we only want to perfect what we are already doing. Krishna can give us siddhis whenever he likes and take them away from us whenever he likes. We have no fear in bhakti and the path is so simple to follow. 

This is what I learnt from the extract that follows. 

Exceprt from the book:

Only by serving Kṛṣṇa can one attain peace, not by yoga practices beginning with yama and niyama

Everyone was fully satisfied by hearing the kīrtana, and they embraced the singer. As the kīrtana finished many sādhus gradually came and sat and began talking on various topics. At that time Haridāsa Bābājī said, “Only the devotees of Kṛṣṇa are blessed. Wherever they may be, they are on the right path. We are servants of their servants.”

In support of this statement, Premadāsa Bābājī said, “Bābājī spoke rightly. In the Śrīmad Bhāgavatam (1.6.35) it is stated:

yamādibhir yoga-pathaiḥ
kāma-lobha-hato muhuḥ
mukunda-sevayā yadvat
tathātmāddhā na śāmyati

“Yama, niyama, āsana, prāṇāyāma, pratyāhāra, dhyāna, dhāraṇā, and samādhi these are aṣṭāṅga-yoga. It is true that by these practices one may achieve peace, but sometimes in the process one may be overwhelmed by lust and greed. Then instead of attaining peace one may enjoy some yogic opulences for sometime before ultimately falling. But in the devotional service of Lord Kṛṣṇa, there is no fear of irrelevant fruits, for the servants of Kṛṣṇa certainly attain peace.’”

When a yogi in the assembly advocates the superiority of yoga over arcana, there was a request for a settlement on the topic

At that time there was an aṣṭāṅga-yogi present in Paṇḍita dāsa Bābājī’s assembly. Although he was a Vaiṣṇava, he had achieved perfection after practicing prāṇāyāma for a long time. As a result, he gave more importance to aṣṭāṅga-yoga than to the nine-fold process of bhakti. Being slightly dissatisfied with Premadāsa Bābājī’s statement, he said, “Bābājī! Don’t disregard the yoga-śāstras. The yogis can give up eating and sleeping and live for a very long time. Can you render devotional service as seriously as they can? Therefore you should know that yoga is superior to arcana.”

Vaiṣṇavas are naturally not inclined to argue. No one, however, liked the yogi’s statement minimizing the importance of devotional service over yoga practice. Everyone remained speechless. Feeling almost insulted, the yogi requested Paṇḍita dāsa Bābājī for his conclusion.

Paṇḍita dāsa Bābājī establishes the superiority of devotional service over yoga

At first Paṇḍita dāsa Bābājī was not inclined to enter into argument, but when the yogi repeatedly assured him that he would accept his conclusion, Bābājī began to speak.

“The only goal of all yoga practice and devotional service is Bhagavān, who is worshiped by all living entities. The living entities are basically classified in two categories—one is pure and one is conditioned. The pure living entity is one who has no material connection, and the conditioned entity is one who has material connection. The sādhaka is certainly a conditioned soul, while the pure entity has nothing to practice. The basic difference between the conditioned and pure living entities is that the latter is situated in his constitutional position. His only activity is spiritual engagement, and his nature is pure bliss. The conditioned living entity, being bound by material nature, accepts materially designated duties that are of mixed material and spiritual qualities. When one gives up materially designated duties and accepts pure duties, that is called liberation. Pure love is the constitutional activity of the soul and cannot be differentiated from liberation. The liberation sought by yoga practice is the same as love of Godhead attained by devotional service. Therefore the ultimate result of both practices is one. For this reason the scriptures portray the foremost devotee Śukadeva as a great yogi and the foremost yogi Mahādeva as a great devotee. The main difference between yoga and devotional service is this: in the strict practice of yoga, when one attains samādhi by giving up false designations, he attains his constitutional position—that is, prema is awakened. There is fear, however, that in the long process of giving up false designations the sādhaka may become captivated by insignificant by-products and fall down before attaining the ultimate goal. On the other hand, in devotional service there is only discussion of prema. Devotional service is simply the cultivation of the science of love of God. When all activities are meant for cultivating the ultimate result, there is no fear of useless results. The means are the end, and the end is the means. Therefore devotional service is easier than the practice of yoga and should be accepted in all respects.”

Showing the inferiority of the yoga path

“The domination over material nature attained in the practice of yoga is only a temporary result. In that position the ultimate result may be far off and time and again impediments are observed. In the path of yoga there are hindrances at every step. First, at the time of practicing yama and niyama, religiosity is awakened, and as a result of attaining this insignificant result one becomes known as religious-minded, even though no attempt has been made to achieve prema. Second, during the long period of practicing āsana and prāṇāyāma one achieves a long life free of disease by controlling the breathing. But if there is still no connection with prema, then one’s long life free of disease becomes a source of trouble. Third, although by the process of pratyāhāra one achieves control of the senses, if prema is lacking this is called dry or insignificant renunciation. The reason is that for attaining the ultimate goal, enjoyment and renunciation give equal results. Useless renunciation simply makes one stone-hearted. Fourth, during dhyāna, dhāraṇā, and samādhi, even if material thoughts are removed, if prema is not awakened the living entity loses his individuality. If the understanding, `I am Brahman’ does not awaken pure love, then that results in destruction of his existence. Therefore, please consider: the ultimate goal of yoga is excellent, but the path is full of difficulties. You are a Vaiṣṇava as well as a yogi, therefore you can understand my words without bias.”

Before Paṇḍita dāsa Bābājī even finished his statement, all the Vaiṣṇavas exclaimed, “Sādhu! Sādhu!”

Though pleased, Yogi Bābājī advocates the usefulness of yoga over devotional service in the matter of sense control

Yogi Bābājī said, “Bābājī, your conclusive statement is excellent, but there is one thing I would like to say. I had properly practiced the nine-fold process of devotional service, beginning with hearing and chanting, previous to learning yoga. But frankly I tell you that in every activity I used to look for sense gratification. I could not free my heart from false designations as described in Vaiṣṇava instructions on conjugal rasa. I was able to taste conjugal rasa only after practicing pratyāhāra, and now I have no desire for sense gratification. My nature has completely changed. There is arrangement for prāṇāyāma in the path of arcana, so I feel that pratyāhāra practice is also seen in the instructions of bhakti-yoga. Therefore I feel that yoga practice is necessary.”

By dry speculation or practice the sādhaka will certainly fall down if the limbs of bhakti are used as fruitive rituals for sense gratification